Flood Control
High water is a natural phenomenon: rivers may flood as a result of persistent rainfall and snow melting. Since the natural floodplains are often populated and subject to intensive economic exploitation, flood damage involves material loss as well as a risk to human life. Flood control primarily takes the form of technical measures such as building barrages, water retention basins, dams, and dikes. Ecological measures aim at natural retention of water by the protection and renaturalization of floodplains and retention areas.
Forecasts and simulations identifying flood risk areas for certain water level values (e.g. hundred-year flood) are necessary for deciding on the necessity and scope of flood control measures.
Color-coded DSM Lahn
© BfG, Germany
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High-precision digital terrain models, such as those produced with aerial laser scanning, are vital as the basis for hydraulic determinations of flood risk areas and risk analyses. Aerial laser scanning provides high-resolution basic data for numerous applications and preventive measures for the flood prevention and water resources management sector:
- Calculation of hydraulic simulations (1D and 2D)
- Determining flood areas
- Producing flood risk maps and risk analyses
- Producing basic planning principles for disaster control
- Recording drainage channels
- Measuring water levels
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Relief image DSM Frankfurt/Oder
© DLR, DFD-AN, Germany
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Profiles and cross sections used in hydraulic simulations can be extracted at any location from the area-wide elevation models.
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Cross section Wolterdingen
© Gewässerdirektion Riedlingen, Germany
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A problem posed in the further processing of aerial laser scanning data for applications relating to water resources management is the extremely high data volume of the raster elevation models. High accuracies and high data densities are vital in changing topography, but often redundant in flat, planar areas. By expedient data thinning in the form of a Triangular Irregular Network (TIN), the data volume is greatly reduced without losing the essential information relevant to water resources management.
Danube forecasts
© Wald + Corbe, Germany
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In the Danube flood risk analysis, TopoSys-supplied DSM and DTM elevation models served as a main processing basis for producing the hydraulic simulation model, for determining the flood areas and for forecasting diverse scenarios.
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